Identifying predictors of healthcare utilization and costs in COPD patients over 18 months: first longitudinal results of the COSYCONET cohort

Background: COPD is associated with excess healthcare utilization and represents high costs to health systems. This study reports trends in healthcare utilization and healthcare costs and identifies predictors of cost changes. Methods: 1904 COPD patients participated in the baseline and 18 months follow-up visit of the German COSYCONET cohort study. Costs were calculated from a societal perspective. Predictors of changes in direct costs at the follow up visit were identified by gamma regression models using baseline information on GOLD grade, age, sex, education, BMI, smoking status, comorbidity count, years since COPD diagnosis, symptoms, and exacerbation history. Adjusted mean direct costs at baseline and follow-up were obtained through generalized estimating equation model. Results: Inflation adjusted mean annual direct costs increased by 5 % (non-significant). Besides direct costs at baseline, higher baseline COPD grades, a history of severe exacerbations in the previous 12 months and comorbidity count >3 were significantly associated with higher total direct costs at the follow-up visit. No statistically significant effects were found for smoking status, years since COPD diagnosis and symptoms (with the exception of dyspnea). Adjusted mean direct costs increased between baseline and follow-up (except in the case of GOLD grade 4). Nevertheless, selective drop out may have led to an underestimation of cost increase. Conclusions: Our findings underline the importance of managing symptoms, exacerbations and comorbidities in the treatment of COPD patients to control the development of direct healthcare costs of COPD over time.